Explosive charge ignition system

ABSTRACT

An ignition system particularly for setting off an explosive charge includes an inductive connection, between an electrical ignition system for the charge and a feed voltage source for actuating the system, by means of transformer windings. The electrical ignition system includes an electrical ignition element which is actuated by the voltage induced in two coils, or transformer winding sections, of the ignition system which are wound in an opposite sense and arranged in series. The transformer winding of the ignition system is harmonized with the transformer winding having the feed voltage applied thereto and which may be inductively coupled to the transformer winding of the ignition system. The transformer winding having the feed voltage applied thereto also comprises two coils, or winding sections, wound in an opposite sense. The construction includes plug type connections, for example in the form of a female member or bushing which is adapted to receive a plug member or male part, the two parts having corresponding spaced inductive coils which align in the plugged in arrangement. The coils may also be formed on a flat plate in side-by-side relationship so that when a transmitting set arranged on one plate is superimposed on a receiving set on another plate, the corresponding coils may be superimposed.

United States Patent Spies 1541 EXPLOSIVE CHARGE IGNITION SYSTEM [72] Inventor: Johann Spies, Pfaffenhofen, Ger- [73] Assignee:

tung, Muenchen, Germany Jan. 2, 1970 [21} Appl. No.: 290

[22] Filed:

30 Foreign Application Priority Data Jan. 11,1969 Germany ..P19 01271.6

[52] US. Cl ..l02l70.2 R, 336/83, 336/200,

336/DlG. 2 [51] Int. C|.......F42c 11/04, F42c 11/00, F42c 15/40 [58] Field of Search ..336IDIG. 2, 206; l02/l9.2,

1151 3,682,098 [451 Aug. 8, 1972 Primary Examiner-Samuel W. Engle Assistant Examiner-Thomas l-I. Webb Attorney-McGlew and Tuttle ABSTRACT An ignition system particularly for setting off an explosive charge includes an inductive connection, between an electrical ignition system for the charge and a feed voltage source for actuating the system, by means of transformer windings. The electrical ignition system includes an electrical ignition element which is actuated by the voltage induced in two coils, or transformer winding sections, of the ignition system which are wound in an opposite sense and arranged in series. The transformer winding of the ignition system is harmonized with the transformer winding having the feed voltage applied thereto and which may be inductively coupled to the transformer winding of the ignition system. The transformer winding having the feed voltage applied thereto also comprises two coils, or winding sections, wound in an opposite sense. The construction includes plug type connections, for example in the form of a female member or bushing which is adapted to receive a plug member or male part, the two parts having corresponding spaced inductive coils which align in the plugged in arrangement. The coils may also be formed on a flat plate in side-by-side relationship so that when a transmitting set arranged on one plate is superimposed on a receiving set on another plate, the corresponding coils may be superimposed.

7Clains,3DrawlngHgures PATENTEDAUE 8 m2 INVENTOR Johann Spies fifiludrma ATTORNEYS I EXPLOSIVE CHARGE IGNITION SYSTEM SUMMARY OF THE INVENTION This invention relates in general to ignition systems for explosives and in particular to a new and useful inductive connection between an electrical ignition system of an explosive charge and a feed voltage source by means of transformer windings.

Inductive connections for supplying the electrical ignition system of powder charges with energy are known, for instance in connection with missile launchers as indicated in US. missile, No. 2,640,417. In this known device, a missile having a first transformer winding, the electrical ignition system and the powder charge in the form of a rocket propellant, is launched from a firing tube. The firing tube has a second transformer winding connected to a suitable feed voltage source and inductively coupled with the first transformer winding in the firing position of the missile.

Even though the first transformer winding which is housed in the missile is enclosed by a steel shell which shields it against interferring magnetic fields, it is nevertheless possible to induce voltages into this winding which is sufficient to ignite the rocket propellent especially when the interfering magnetic fields are strong. Such an undesired ignition of the propellant must be avoided if only for safety reasons. When it is desired to use such inductive connections for igniting not only missile propellants but also explosive charges of projectiles or to furnish the energy for such ignition, then an undesired ignition due to interferring magnetic or electrostatic fields must be avoided under all circumstances.

An object of the present invention is therefore to improve the known inductive connections so that an undesired triggering of the electrical ignition system is avoided with certainity. In accordance with the invention, the transformer winding of the ignition system consists of two coils which are wound in an opposite sense and arranged in series. Because of the division of the transformer winding into two coils arranged in series electrically and wound in an opposite sense and which are arranged for coupling inductively with two coils of the feed voltage source which are wound in a corresponding manner, the effects of interfering magnetic fields are cancelled out in the transformer (receiver) winding connected with the ignition system so that no undesired triggering of the ignition system because of such interference can occur.

According to a feature of the invention, the electrical ignition element of the ignition system is short circuited by the coils of the transformer windings. The ohmic impedance value of the transformer winding which is connected with the ignition system is so low that an effective electrical short circuit of the electrical ignition element occurs so that an undesired triggering due to electrostatic charges is thus avoided with certainity. This is required particularly for the storing of war heads which are equipped with such an ignition system or the storing of explosive charges having a disrupted inductive connection.

The transformer windings of the feed voltage source and the transformer windings of the ignition system are dimensioned so that a matching of the impedance between the feed voltage source and the ignition system takes place. By such a design the transformer windings required for the inductive transmission are utilized also for the transformation of the output impedance of the feed voltage source to the input impedance of the ignition system. This means, for example, that even relatively low ohmic electrical ignition elements can be triggered safely by means of a feed voltage source having a high output impedance.

The inventive inductive connection is advantageously constructed in a traditional manner as a coaxial plug connection with concentrically arranged overlapping transformer windings. The transformer windings may also be arranged as flat coils so that a plug in type connection is formed by the superposition of two touching plan parallel plates containing the respective sets of transformer windings in the form of flat coils.

Accordingly, it is an object of the invention to provide an improved inductive connection between an electrical ignition system of an explosive charge and a feed voltage source by means of transfonner windings wherein the transformer winding of the ignition system comprises two coils wound in an opposite sense and connected in series and which advantageously includes an electrical ignition element which is short cireuited by the transformer coils.

A further object of the invention is to provide an electrical ignition system including an electrical ignition element which is short cireuited by transformer coils which are arranged to receive induced voltage from a feed voltage source through a second set of transformer coils, each transformer coil being divided into two oppositely wound coils connected in series and dimensioned so that a matching of the impedance between the feed voltage source and the ignition system takes place.

A further object of the invention is to provide an inductive connection which includes two transformer coils arranged in series and wound in an opposite sense and advantageously incorporated as a plug in type connection which when completed arranges one set of coils over the other set, the plug in connection being either a coaxial type or in the form of flat superimposed plates having the respective coils.

A further object of the invention is to provide an inductive connection particularly for the ignition system of an explosive charge which is simple in design, rugged in construction, and economical to manufacture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. I is an axial sectional view of a detached plug in type inductive connection for an explosive charge constructed in accordance with the invention;

FIG. 2 is a top plan view of a single one of a flat plate type plug connection of another embodiment of the invention; and

FIG. 3 is a schematic electrical wiring diagram of the plug connection.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings in particular, the invention embodied therein in FIG. 1, includes a plug connection for an inductive connection between an electrical ignition system of an explosive charge and its feed voltage source. In this embodiment the inductive connection is preferably constructed in the manner of a traditional coaxial plug connection which includes a bushing part or female part 1 which carries, at two axially spaced locations, two cylindrical coils 2 and 3. The coils 2 and 3 are electrically connected together in series and are oppositely wound.

The bushing part 1 is arranged to receive a plug part or male part 4 which includes two cylindrical coils 5 and 6 which are arranged at spaced axial locations corresponding in spacing to that of the coils 2 and 3 and located so that they will be covered by the coils 2 and 3 of the bushing part when the plug connection is assembled. The coils 5 and 6 are connected in series and are oppositely wound in a manner similar to that of the coils 2 and 3.

In the embodiment indicated in FIG. 2, a plug connection is made by two identical plate members only one of which, plate 7, is indicated. The plate 7 carries two flat coils 8 and 9 which are connected together in series and which are oppositely wound. The other part (not shown) is constructed in a similar manner and carries two additional fiat coils (not shown) which are wound correspondingly to the coils 8 and 9 and are connected in series and are arranged so that they cover the coils 8 and 9 when the additional plate is superposed on the plate 7.

A simplified electrical wiring diagram for the inductive connection is shown in FIG. 3, and it includes an ignition system 10 having a transformer winding 11 for operating an electrically actuated ignition element 12. The transformer winding includes two coils Ill and 112 which are wound in an opposite sense and arranged in series electrically. These coils correspond for example, to the coils 2 and 3 of FIG. 1. A feed voltage source in an energizing circuit 22 acts upon a second transformer winding 21 which also comprises two coils 211 and 212 which are wound in respective opposite directions and connected together in series. Because the respective coils Ill and 211 and 112 and 212 which communicate with each other inductively are wound in the same sense, the voltages induced in the coils Ill and 112 add up to a total voltage which safely triggers the ignition element 12 when the ignition system 10 and the feed voltage system 22 are connected with each other inductively through transfomter winding 11 and 21. Due to the low ohmic resistance of transformer winding 11, when not inductively coupled to transformer winding 21, this transformer winding 1 l, with its sections 111 and 112, acts as a short circuit for the ignition element 12, protecting the latter against energization by stray electrostatic or electromagnetic fields.

By using suitable materials to fon'n shields or shielding elements 13 and 14 the transformer windings 11 and 21 are shielded against interfering magnetic fields when they are in the unassembled condition through the action of the shields l3 and 14 which act as magnetic circuits. In the assembled conditions these shielding elements 13 and 14 favor the inductive coupling because the magnetic impedance is relatively small for the magnetic flux which developes between the transformer windings 11 and 21. The number of windings of the transformer windings 11 and 21 are so harmonized mutually that a matching of the impedance of the feed voltage source 20 to the electrical ignition element 12, as a consumer of the energy furnished by the feed voltage source 20, takes place.

Besides the advantageous electrical properties of the inductive connection such as insensitivity to interfering magnetic fields and electrical short circuiting of the electrical ignition element in the unassembled state of the plug connection, the arrangement offers the additional advantage that it can be built so as to be very strong and robust mechanically. The arrangement is such that for certain applications in modern weapons technology explosive charges directly connected to the plug part of the plug connection can be triggered without damaging or even destroying the reusable bushing part 1 even though there are considerable shock wave loads which occur.

What is claimed is:

1. An ignition circuit system for inductive connection to energize an igniter for an explosive charge comprising, in combination a transformer, an ignition circuit including an electrically energized igniter connected in series with a first winding of said transformer including two first coils wound in respective opposite directions and in series with each other; an energizing circuit including a source of electric potential connected in series with a second winding of said transformer including two second coils wound in respective opposite directions and in series with each other; and respective connection and mounting means independently mounting portion of the circuit and selectively movable into cooperating relation with each other with each second coil positioned adjacent a correspondingly located respective first coil; the winding direction of each second coil with respect to that of its correspondingly located respective first coil being such that said transformer windings are effectively coupled inductively when said mounting means are in said cooperating relation with each other, whereby to apply the potential of said source to said igniter to energize said igniter.

2. An ignition circuit system, according to claim 1, wherein said two first coils have a low ohmic resistance so as to maintain the potential at opposite terminals of said igniter at the same value to prevent accidental energization of said igniter by stray electric fields, said two first coils thus constituting, when said connection and mounting means are not in cooperating relation with each other, an effective short circuit for said igniter.

3. An ignition, according to claim 1, wherein said first and second windings of said transformer are dimensioned to produce a matching of the impedance between said source and said igniter when said connection and mounting means are moved into said cooperating relation with each other.

4. An ignition circuit system according to claim 1, wherein said first and second transformer winding coils comprise flat coils.

5. An ignition circuit system inductive connection, according to claim 1, including respective magnetic material means shielding each of said first and second coils against interfering magnetic fields when said connection and mounting means are not in said cooperat ing relation with each other; said magnetic material means having a low magnetic resistance enhancing the inductive coupling between said first and second winding of said transformer when said connection and mounting means are moved into cooperating relation with each other.

correspondingly located respective first coil.

7. An inductive connection, according to claim 6. wherein said plug-in type connector is of a coaxial type and includes a female bushing part and a male plug part.

i t l I II 

1. An ignition circuit system for inductive connection to energize an igniter for an explosive charge comprising, in combination a transformer, an ignition circuit including an electrically energized igniter connected in series with a first winding of said transformer including two first coils wound in respective opposite directions and in series with each other; an energizing circuit including a source of electric potential connected in series with a second winding of said transformer including two second coils wound in respective opposite directions and in series with each other; and respective connection and mounting means independently mounting portion of the circuit and selectively movable into cooperating relation with each other with each second coil positioned adjacent a correspondingly located respective first coil; the winding direction of each second coil with respect to that of its correspondingly located respective first coil being such that said transformer windings are effectively coupled inductively when said mounting means are in said cooperating relation with each other, whereby to apply the potential of said source to said igniter to energize said igniter.
 2. An ignition circuit system, according to claim 1, wherein said two first coils have a low ohmic resistance so as to maintain the potential at opposite terminals of said igniter at the same value to prevent accidental energization of said igniter by stray electric fields, said two first coils thus constituting, when said connection and mounting means are not in cooperating relation with each other, an effective short circuit for said igniter.
 3. An ignition, according to claim 1, wherein said first and second windings of said transformer are dimensioned to produce a matching of the impedance between said source and said igniter when said connection and mounting means are moved into said cooperating relation with each other.
 4. An ignition circuit system according to claim 1, wherein said first and second transformer winding coils comprise flat coils.
 5. An ignition circuit system inductive connection, according to claim 1, including respective magnetic material means shielding each of said first and second coils against interfering magnetic fields when said connection and mounting means are not in said cooperating relation with each other; said magnetic material means having a low magnetic resistance enhancing the inductive coupling between said first and second winding of said transformer when said connection and mounting means are moved into cooperating relation with each other.
 6. An ignition circuit system, as claimed in claim 1, in which said first coils are arranged in axially spaced relation on one part of an interengageable plug-in type connector, and said second coils are arranged in corresponding axially spaced relation on the other part of saId interengageable plug-in type connector; each part of said plug-in type connector constituting a respective one of said mounting means; whereby, when said plug-in type connector has its parts interengaged, each second coil is positioned in inductive relation with its correspondingly located respective first coil.
 7. An inductive connection, according to claim 6, wherein said plug-in type connector is of a coaxial type and includes a female bushing part and a male plug part. 